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121.
精氨酸、谷氨酰胺、谷氨酸、脯氨酸、天冬氨酸、天冬酰胺、乌氨酸和瓜氨酸可在大多数哺乳动物(包括猪)体内通过复杂的器官间代谢进行相互转化.小肠、肾脏和肝脏是这些氨基酸代谢的主要场所,皮质醇则是这些代谢的一个重要调控激素.由于这些氨基酸(除乌氨酸和瓜氨酸之外)通常大量地存在于植物和动物的组织蛋白中,所以养猪生产者习惯上不大关心猪日粮中精氨酸族氨基酸的添加问题.然而,最近的研究结果表明,这些氨基酸在养分代谢和免疫应答上起着重要的调控作用,从而会影响猪的饲料利用率.精氨酸和谷氨酸就是其中的典型代表,它们具有明确的功能,因此被广泛地应用于猪肉生产中.由瓜氨酸在小肠中合成减少所引起的精氨酸缺乏,是限制哺乳仔猪获得最佳生长性能的主要因素.酶学和代谢学研究结果均表明,对于7~21日龄哺乳仔猪而言,肠上皮细胞线粒体内N-乙酰谷氨酸的生物利用率低下应为通过谷氨酸和脯氨酸合成瓜氨酸受到阻碍负责.因此,无论在日粮中添加精氨酸还是口服N-胺基甲基麸胺酸(N-carbamylglutamate,N-乙酰谷氨酸的一种稳定的代谢类似物)都能提高哺乳仔猪的肌肉蛋白合成率和增重.此外,在早期断奶的仔猪日粮中添加谷氨酸已可防治其小肠萎缩.并且提高了仔猪的生长性能.值得注意的是,在妊娠30~114d的小母猪日粮中添加精氨酸,也会显著地提高产活仔数和窝初生重.大规模地使用饲料级精氨酸和谷氨酰胺为提高全球养猪生产的动物健康和养分利用率展现了广阔的前景. 相似文献
122.
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124.
Drug-sensitivity of 99 isolates of coccidia from broiler farms 总被引:7,自引:0,他引:7
Coccidia were isolated from 99 broiler farms in 12 broiler-producing states and tested for sensitivity to contemporary anticoccidial drugs. The isolates usually comprised two or more species, including 92 Eimeria acervulina, 47 E. maxima, 28 E. tenella, and 10 E. brunetti. Based on intestinal-lesion-score reduction of 30% or more, 38% of isolates were resistant to monensin (110 ppm), 29% to salinomycin (60 ppm), 20% to nicarbazin (125 ppm), and 46% to amprolium + ethopabate (125 + 4 ppm). Isolates with 50% or greater reduction of lesion scores were considered sensitive. Thirty-three percent were sensitive to monensin, 53% to salinomycin, 67% to nicarbazin, and 39% to amprolium + ethopabate. Other isolates had intermediate response to drugs and were considered to have "reduced sensitivity." There was some evidence for incomplete cross resistance to the polyether, ionophorous products. 相似文献
125.
Fuller ML 《Science (New York, N.Y.)》1905,21(541):748-749
126.
Mastomys natalensis, Aethomys chrysophilus and Saccostomus campestris are three common and widespread rodent species in the Kruger National Park. Chromosomal and protein electrophoretic investigations reveal that these species are in fact complexes of morphologically similar, though genetically distinct, species. Their respective distributions in the Kruger National Park are reported and species diagnostic characters (diploid chromosome number, genitalia, spermatozoa and electromorphs) are presented for the practical identification of the cryptic species. The value of a genetical approach to resolving cryptic species is emphasized with respect to ecological studies. 相似文献
127.
Pamela H. Templer Andrew F. Schiller Nathan W. Fuller Anne M. Socci John L. Campbell John E. Drake Thomas H. Kunz 《Biology and Fertility of Soils》2012,48(4):413-424
Projected changes in climate for the northeastern USA over the next 100 years include a reduction in the depth and duration
of the winter snowpack, which could affect soil temperatures and frost regimes. We conducted a snow-removal experiment in
a northern hardwood forest at the Hubbard Brook Experimental Forest in central New Hampshire over 2 years to induce soil freezing
and evaluate its effect on the abundance, richness, and diversity of soil arthropods during the growing season. Snow removal
at the beginning of winter increased the depth and duration of soil frost, decreased soil temperatures, and led to a reduced
abundance of some arthropod taxa, including Araneae (reduced by 57%; P = 0.0001), Pseudoscorpionida (75%; P < 0.0001), Hymenoptera (57%; P = 0.0033), Collembola (24%; P = 0.0019), adult Coleoptera (23%; P = 0.0057), and larval Diptera (33%; P < 0.0001) and an increase in other taxa, including Hemiptera (increased by 7%; P = 0.032). Taxa that did not respond significantly to snow removal included Chilopoda (P = 0.55), Acari (P = 0.66), Diplopoda (P = 0.66), adult Diptera (P = 0.54), and larval Coleoptera (P = 0.39). A delayed snowpack over two winters also resulted in decreased arthropod richness by 30% (P < 0.0001) and Simpson’s index of diversity by 22% (P = 0.0002) during the two subsequent growing seasons. Results of this study demonstrate that predicted changes in the winter
snowpack and depth and duration of soil frost may reduce the abundance and alter the community composition of arthropods living
in the forest floor of northern hardwood forests, which could have implications for the structure and function of northern
forest ecosystems. 相似文献
128.
Mark C. Fuller Amy S. Kapatkin Kenneth A. Bruecker Ian G. Holsworth Philip H. Kass Kei Hayashi 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(8):757-764
Use of the tibial mechanical joint orientation angles is now the standard of care for evaluating tibial deformities, although they have not been used to evaluate dogs with cranial cruciate ligament (CrCL) rupture. The objective of this study was to compare the tibial mechanical joint orientation angles and tibial plateau angle (TPA) between dogs with bilateral CrCL rupture (BR) and unilateral CrCL rupture with (UR-SR) and without subsequent contralateral CrCL rupture (UR-w/o-SR) as risk factors for subsequent contralateral CrCL rupture. Twenty dogs (21.7%) were classified as BR, 38 (41.3%) were classified as UR-SR, and 34 (37.0%) were classified as UR-w/o-SR. The tibial mechanical joint orientation angles and TPA, in the range studied (< 35°), were not statistically different for dogs with BR, UR-SR, and UR-w/o-SR, and were not significant risk factors for subsequent contralateral CrCL rupture. 相似文献
129.
上期回顾:上期主要介绍了母猪乳汁中精氨酸族氨基酸的含量及其在哺乳母猪乳腺组织中的代谢,和谷酰胺和胱氨酸在仔猪营养中的作用. 4 精氨酸在新生仔猪营养中的作用 4.1 精氨酸合成对维持其在哺乳仔猪体内的自动动态平衡所起的关键作用 相似文献
130.
O'Brien M Nielsen KF O'Kiely P Forristal PD Fuller HT Frisvad JC 《Journal of agricultural and food chemistry》2006,54(24):9268-9276
Secondary metabolites produced by Penicillium paneum and Penicillium roqueforti from baled grass silage were analyzed. A total of 157 isolates were investigated, comprising 78 P. paneum and 79 P. roqueforti isolates randomly selected from more than 900 colonies cultured from bales. The findings mostly agreed with the literature, although some metabolites were not consistently produced by either fungus. Roquefortine C, marcfortine A, and andrastin A were consistently produced, whereas PR toxin and patulin were not. Five silage samples were screened for fungal metabolites, with two visually moldy samples containing up to 20 mg/kg of roquefortine C, mycophenolic acid, and andrastin A along with minor quantities (0.1-5 mg/kg) of roquefortines A, B, and D, festuclavine, marcfortine A, and agroclavine. Three visually nonmoldy samples contained low amounts of mycophenolic acid and andrastin A. The ability of both molds to produce a diverse range of secondary metabolites in vitro and in silage should be a concern to livestock producers. 相似文献